On 9/25/07, Brett Cannon <[EMAIL PROTECTED]> wrote: > On 9/25/07, Guido van Rossum <[EMAIL PROTECTED]> wrote: > > OK, Jeffrey's and Adam's patches were helpful; it looks like the > > damage done by making bytes immutable is pretty limited: plenty of > > modules are affected, but the changes are straightforward and > > localized. > > > > So now I have an idea that goes a little farther. It relates to > > Talin's response (second message in this thread if you're using gmail) > > and acknowledges that there are some good use cases for mutable bytes > > as well (as I've always maintained). > > > > How about we take the existing PyString implementation (Python 2's > > str, currently still present as str8 in py3k), remove the locale and > > unicode mixing support, and call it bytes. Then the PyBytes type can > > be renamed to buffer. It is well-documented that I don't care much > > about the existing buffer() builtin; it can be renamed to memview for > > all I care (that would be a more descriptive name anyway). > > > > This would provide a much better transitional path for 2.x code > > manipulating raw bytes using str instances: just change "..." into > > b"..." and str into bytes. (Of course, 2.x code that is confused about > > bytes vs. characters will fail hard in 3.0 as soon as a bytes and a > > str instance meet -- this is already the case in the current 3.0 code > > base and will remain unchanged.) > > > > It would mean more fixes beyond what Jeffrey and Adam did, since > > iterating over a bytes instance would return a bytes instance of > > length 1 instead of a small int, and the bytes constructor would > > change accordingly (no more initializing a bytes object from a list of > > ints). > > > > +0. While 2to3 would be able to help more, the methods that will be > ripped out will make the ease in transition from this a lot less.
Compared to what? The methods to be ripped out are already not available on bytes objects. > Plus you can have immutable bytes in a way by passing the current > bytes to tuple. At what cost? tuple(b"x"*100) is a tuple of length 100. > > The (new) buffer object would also have to change to be more > > compatible with the (new) bytes object -- bytes<-->buffer conversions > > should be 1-1, and iterating over a buffer instance would also have to > > return a length-1 buffer (or bytes???) instance. > > Return a byte. If you want a mutable length-1 thing you should have > to do a length 1 slice. Otherwise its an index operation and you want > what is stored at the index, which is an immutable byte. OK. Though it's questionable even whether a slice of a mutable bytes object should return a mutable bytes object (as it is not a shared view). But as that is what PyBytes currently do it is certainly the easiest... -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
